With the increased prevalence of mobile communication devices, it has recently become necessary to monitor interference of mobile communication devices with other systems, such as hearing aids. As mobile communication devices are commonly held to the ear, it is possible that, where the person holding the device has a hearing aid inserted into the person's ear, the mobile communication device may interfere with signals in the hearing aid and degrade its performance.
One existing arrangement for HAC testing comprises a stand for supporting the mobile communication device during the testing and a reference grid or locater. The stand has vice-like grips for gripping the mobile communication device during the testing, and a base positionable on a flat surface. The position of the grips is movable relative to the base about several axes and/or planes of movement. The material of the stand is selected to have a dielectric constant that is low.
In use, the mobile communication device is fixed between the grips of the stand and positioned so as to have it's audio output located at a certain position with respect to the reference grid, following which the electric or magnetic field strength is measured at particular locations around the audio output while the mobile communication device is transmitting a signal.
Measurements obtained during HAC testing have a certain amount of inherent uncertainty. Reducing this HAC measurement uncertainty can be important for enforcing the compatibility standard and helping manufacturers in device development.